PrimaryKey
Annotation marking a field as a primary key inside Realm.
Only one field in a RealmObject class can have this annotation, and the field should uniquely identify the object.
This annotation applies to the following primitive types: String, Byte, Char, Short, Int, Long, org.mongodb.kbson.ObjectId and RealmUUID, as well as their nullable variants.
It cannot be applied on a property that also has a FullText annotation.